Telegraph switching system



Sept. 2, 1930. c. E. LOMAX TELEGRAPH SWITCHING SYSTEM Filed April so. 1928 1mm Clarence E. Lnmax NN AN Patented Sept. 2, 1930 UNITED STATES- PATENT OFFICE CLARENCE E. LOMAX, OF OAK PARK, ILLINOIS, ASSIGNOR TO RESERVE HOLDING GOM- PANY, OF KANSAS CITY, MISSOURI, A,COR PORATION OF DELAWARE TELEGRAPH SWITCHING SYSTEM Application filed April 80,

My invention relates to improvements in telegraph switching systems and particularly to printing telegraph or teletype systems.

The object of my invention is to utilizenor- 5 mally closed circuits extending between the sending stations and receiving stations 'for selecting idle receiving stations and for thereafter transmitting signals from the sending station to the selected receiving station.

This present invention is an improvement over the system disclosed in my prior Patent N 0. 1,581,844 granted April 20,1926, in which a normally closed circuit is also utilized for controlling receiving stations from sending stations. V

In the present instance, each sending station is provided-with transmitting and receiving equipment such as illustrated and described on page 226 in Telegraph and Telephone Age of May 16, 1922. This article describes both the receiving and transmitting mechanism. The combined transmitting and receiving unit is illustrated in Figure 1, the receiving unit is illustrated in Figure 2 while the transmitting unit is illustrated in Figure 3. The sending station would therefore be equipped with the mechanism illustrated in. Figure 1 while each receiving station would be equipped with the receiving unit illustrated in Figure 2.

Eachsending station is provided with a single step bystep switch for selecting an idle receiving station. The switch is equipped with three wipers and three sets of bank contacts with which the wipers co-operate. The bank contacts of the switches are multipled so any receiving station maybe selected b an switch.

The swltch is set in operation by opening the circuit at the sending station by means of a simple form of switch or key. The opening of the circuit causes the switch to'auto-' matically step and bring, its wipers in en-. -gagement with contacts extending to an idle receiving station. After the selection is made and the circuit closed at the sending station -a signal is operated at each station to indicate such selection.

Referring to the drawin K represents a keyboard, J the print ng ,magnet, A-

1928. Serial in. 278,830.

The various details of my invention will be fully described in tracing a call from a sending to a receiving station.

As shown in the drawing a'normally closed circuit extends from ground through the bank of keys K, winding of printing magnet J, winding of relays A and B contacts of key L, conductor 1, resistance 2, conductor 3, contacts of relays V and E, winding of relay G to volt negative battery to ground. Due to this closed circuit, relays C and A are energized but the printing magnet J being of low resistance is not operated. The polarized relay B likewise, is not operated due to current flowing from negative 110 volt battery through winding of relay C.

The operator at the sending station depressing the key L opens the normally closed circuit causing relays A and C to become deenergized. I Rela C upon restoring prepares the circuit 0 stepping magnet D of the switch S as follows ground, battery 40, contacts of relay U, 7, winding of magnet D, vibrating contacts of magnet D, 8, lower contacts of relay E, 9, contacts of relay C, upper contacts of relay E, 11, wiper and bank contacts 10, to conductor 12, which is multipled to corresponding contacts in the banks of other switches S. In case another switch is engaging corresponding contacts, ground will be connected to conductor 12 as relay E of that switch will be energized and relay C deenergized. In this event ground will be connected to conductor-12 as follows: key R, 14, contacts and wiper 20 of the switch S, 13, contacts of relay C, upper contacts of relay E, 11, contacts and wiper 10, of switch S, to conductor 12. In case mind is connected as described then the swltch magnet D will have its circuit closed causing the switch S to ste until the wiper engages a contact 10 free rom ground. I p

Assuming that the wiper engages the bank contact, and conductor 12 is free from ground, the circuit of relay E will be completed as follows; ground, battery 40, contacts of relay U, 7, winding and contacts of magnet D,

8, make before break contacts of relay E,

winding of relay E, contacts of relay C, 13, 20, 14, contacts of key-R to ground. Relay E disconnects the battery connection through the winding of magnet D and substitutes therefor a battery connection through resistance and remains in an energized condition. The operation of relay E completes the circuit of relay F as follows: ground, contacts of key R, 14, 20, 13, contacts of relay C, upper contacts ofrelay E, 11, 10, 12, contacts of key P, winding of relay F, battery 40 to ground. The operation of relay F completes the circuit of the motor starting relay G of the receiving set, places motor T in operation and lights the signal lamp W.

When the selection has taken place and the key L has been restored, relay B will have its circuit completed and become energized and short circuit winding of-relay A.

The restoration of relay A and key L completes the circuit of the motor M of the sending unit and'causes lamp X to light.

' nipulates the key bank K in accordance with the message desired to be transmitted, which causes impulses to be transmitted to the keyboard 0 and'the printing magnet H of the receiver at station No. 1 in series with the windings of magnet J and relay B. After the message has been transmitted the operator at the receiving station No. 1 operates the release key R disconnecting ground from the winding of relay E causing it to become deenergized and connects the relays to their original condition with the winding of relay G in series with windings of'relays'.A and B and magnet J. The operation of relay A will disconnect the motor M and lamp X while the restoration of relay F will cause the deenergiza- .tion of relay G therefore disconnecting the motor T.

The busy control keys P and P at stations No. 1 and No. 2 respectively, when 0 erated, render the contacts of the switch busy against selection. The operation of key P, for instance, connects ground to the multiple contact over conductor 12. ThlS ground connection would cause the stepping magnet of another switch S to be operated in case its wipers engaged the grounded or busy contact. As before stated, the switch S when rotating has its relay E deenergized andrelay C also deenergized, thus closing the circuit of magnet D as follows: ground, contacts of P, 12, 10, 11, upper contacts of relay E, contacts of relay 0, 9, lower contacts of relay E, 8, contacts and winding of magnet D, 7, contacts of relay U, battery 40, to ground.

In case all the busy keys are operated, such I In case all of the receiving stations are actually busy, then all relays such as F and F will be energized and likewise'connect ground to relay U.

Each receiving station may be provided with. a connector switch and controlling ,mechanism of the type disclosed in my prior Patent No. 1,581,844 of April 20, 1926, for selecting any sending station. The wipers of the connector switch when operated would engage contacts of the banks to which conductors 21 and 22 are connected. This wouldcause the operation of relay V which would disconnect relay CI from the normally closed circuit, but maintain it energized by connecting groundto its winding over conductor 4. r

The receiving mechanism or unit at the sending station would then be controlled over conductor 21. through the connector switch, as disclosed in my prior patent.

While I-have illustrated but a single sending station and two receiving stations, it is to be understood that anynumber of such stations may be operated by simply duplicat- 2. In a tele aph switching system, the combination a sending station and a plurality of receiving stations, an automatic switch for selecting any one of said receiving stations, a normally closed circuit extending from the sending station to the automatic switch, means at the sending station for opening said circuit, the opening of the circuitcausing the automatic switch to select an idle switch to select an idle one of said receiving one of said receiving stations, the selection of said receiving station causing an indication to be made at the sending and receiving stations. I\

3. In a telegraph switching system, the combination of a sending station and a plurality of receiving stations, an automatic switch for selecting any one of said receiving stations, a normally closed circuit extending from said sending station to the automatic switch, means for opening said circuit, the opening of the circuit causing the automatic stations, the selection of said receiving'station causing an indication to be made at the sending and receiving stations upon the closure of said circuit. 0

4. In a telegraph switching system, the combination of a sending station and a receiving station, a normally closed circuit connecting said stations, means for opening and closing said circuit, means controlled during the opening of said circuit for selecting said receiving station, and means for signalling'said stations after said circuit is closed.

5. In a telegraph switching system, the combination of a sending station and a re-' ceiving station, an automaticswitch for selecting said receiving station, means for holding said switch in its selected position for interconnecting said stations, and means controlled at said receiving station for releasingsaid holding-means.

6. In a telegraph switching system, the

combination of a sending station and a re ceiving station, an automatic switch for selecting said receiving station, a normally closed circuit extending from said sending station to said switch, a polarized relay having its winding included in said circuit and normally inoperative, means'controlled by the opening of said circuit for causing the operation of said automatic switch to select said receiving station, and means controlled after said circuit is closed for operating said polarized relay following the selections of said receiving station.

7. In a telegraph switching system, the combination of a sending station and a receiving station, an automatic switch for selecting said receiving station, a normally closed circuit extendingfrom said sending station to said switch, a polarized relay and a magnet having their winding in series with said circuit, means for opening said circuit,

the opening of said circu1t causing the automatic switch to select said receiving station, the closing of said circuit after such selection causing the operation of said polarized relay," the operationof said polarized relay serving to short circuit the winding of'said magnet. a V v 8. In a telegraph switching system, a sendfing station and a plurality of receiving stations,-an automatic switch having access to said receiving stations, a closedpircuit comprising a single conductor extending from saidsending station to said automatic switch, means at said sending station for opening said closed circuit, and means responsive to said opening for operating said automatic switch to select an idle one of said receiving stations.

9. In a telegraph switching system, a pluautomatic switch for each of said sending statlons having access to said receiving starality of sending and receiving stations, an

tions, a normally closed circuit connecting a sending station with its associated automatic ing the closed circuit, means responsive to the opening ofsaidcircuit for operating said automatic switch to select an idle one of said receiving stations, and means for preventing the seizure of said selected receiving station I switch, means at the sending station for openby any other automatic switch while it is'in engagement with said first switch.

10. In a telegraph switching system, a sending station and a plurality of receiving stations, an automatic switch having access to said receiving stations, a normally closed circuit connecting said sending station with said automatic switch, means at said sending station for opening said circuit, means responsiv'e to the opening of said circuit for operating said automatic switch to select an idle one of said receiving stations, and means for preventing saidswitch from operating incase all of said receiving stations are busy.

11. In a telegraph switching system, sending and receiving stations, an automatic switch individual to each sending station and having access to said receiving stations, a I

- ing the signal at said sending station.

12. In a telegraph switching system, sending and receiving stations, an automatic switch individual to 'each' of said sending stations and having access to said receiving stations, a normally closed circuit extending from eachof said sending stations to its'associated switch, signals at said stations, means at said sending stations for opening and closing its associated circuit, means responsive to said opening for operating the associated switch to select an idle one of said receiving stations, means responsive to the selection of said receiving station and the closure of'said circuit for operating the signals at said sending and receiving stations, and means at said receivmg' station for controlling the release of said connection.

In Witness whereof, I hereunto subscribe my name this 28th day of April, A. D. 1928. o CLARENCE E. LOMAX. 

